Muon g-2 and α (MZ2): A new data-based analysis

Abstract

This work presents a complete reevaluation of the hadronic vacuum polarization contributions to the anomalous magnetic moment of the muon, aμhad, VP, and the hadronic contributions to the effective QED coupling at the mass of the Z boson, Δαhad(MZ2), from the combination of e+e-→hadrons cross section data. Focus has been placed on the development of a new data combination method, which fully incorporates all correlated statistical and systematic uncertainties in a bias free approach. All available e+e-→hadrons cross section data have been analyzed and included, where the new data compilation has yielded the full hadronic R-ratio and its covariance matrix in the energy range mπ≤s≤11.2 GeV. Using these combined data and perturbative QCD above that range results in estimates of the hadronic vacuum polarization contributions to g-2 of the muon of aμhad, LO VP=(693.26±2.46)×10-10 and aμhad, NLO VP=(-9.82±0.04)×10-10. The new estimate for the Standard Model prediction is found to be aμSM=(11659182.04±3.56)×10-10, which is 3.7σ below the current experimental measurement. The prediction for the five-flavor hadronic contribution to the QED coupling at the Z boson mass is Δαhad(5)(MZ2)=(276.11±1.11)×10-4, resulting in α-1(MZ2)=128.946±0.015. Detailed comparisons with results from similar related works are given